This generally occurs when you've downloaded LockDown Browser using the wrong web link. Each institution has a unique download link for LockDown Browser, and its vital that you use the correct one. You should avoid using a search engine to locate a download link for your institution.
To resolve this issue, first uninstall the incorrect copy of LockDown Browser and then install the proper version for the institution.
Contact your school's Respondus Campus-wide Local Support Contact for additional assistance in obtaining the correct URL to download LockDown Browser for your school.